pyridoxine

Absorption: Well absorbed from the GI tract.

Distribution: Stored in liver, muscle, and brain. Crosses the placenta and enters breast milk.

Metabolism/Excretion: Converted in RBCs to pyridoxal phosphate and another active metabolite. Amounts in excess of requirements are excreted unchanged by the kidneys.

Half-Life: 15–20 days.

Time/Action Profile ⬆ ⬇

ROUTE	ONSET	PEAK	DURATION
PO, IM, IV	unknown	unknown	unknown

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity to pyridoxine or any component.

Use Cautiously in:

Parkinson’s disease (treatment with levodopa only);
OB: Chronic ingestion of large doses may produce pyridoxine-dependency syndrome in newborn.

Adv. Reactions/Side Effects ⬆ ⬇

Adverse reactions listed are seen with excessive doses only

Neuro: sensory neuropathy, paresthesia

Misc: pyridoxine-dependency syndrome

Interactions ⬆ ⬇

Drug-drug:

Interferes with the therapeutic response to levodopa when used without carbidopa.
Requirements are ↑ by isoniazid, hydralazine, chloramphenicol, penicillamine, estrogens, and immunosuppressants.
↓levels of phenobarbital and phenytoin.

Route/Dosage ⬆ ⬇

Prevention of Deficiency (Recommended Daily Allowance)

PO (Adults and Children >14 yr): 1.2–1.7 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, penicillamine, and estrogen-containing oral contraceptives).
PO (Children 9–13 yr): 1 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, and penicillamine).
PO (Children 1–8 yr): 0.5–0.6 mg/day (larger doses required with cycloserine, ethionamide, hydralazine, immunosuppressants, isoniazid, and penicillamine).
PO (Infants 6–12 mo): 0.3 mg/day.
PO (Infants <6 mo): 0.1 mg/day.

Treatment of Deficiency

PO (Adults ): 2.5–10 mg/day until clinical signs are corrected, then 2–5 mg/day.
PO (Children ): 5–25 mg/day for 3 wk, then 1.5–2.5 mg/day.

Pyridoxine-Dependent Seizures

PO IM IV (Neonates and Infants): 10–100 mg initially, then 50–100 mg/day orally.

Drug-Induced Neuritis

PO (Adults ): Treatment: 100–300 mg/day; Prophylaxis: 25–100 mg/day.
PO (Children ): Treatment: 10–50 mg/day; Prophylaxis: 1–2 mg/kg/day.

Isoniazid Overdose (>10 g)

IM IV (Adults and Children ): Amount in mg equal to amount of isoniazid ingested given as 1–4 g IV, then 1 g IM every 30 min.

Availability ⬆ ⬇

(Generic available)

Capsules: 250 mg^OTC
Tablets: 25 mg^OTC; 50 mg^OTC; 100 mg^OTC; 250 mg^OTC; 500 mg^OTC
Extended-release tablets: 200 mg^OTC; 500 mg^OTC
Solution for injection: 100 mg/mL

Assessment ⬆ ⬇

Assess patient for signs of vitamin B₆ deficiency (anemia, dermatitis, cheilosis, irritability, seizures, nausea, and vomiting) before and periodically throughout therapy. Institute seizure precautions in pyridoxine-dependent infants.

Lab Test Considerations:

May cause false elevations in urobilinogen concentrations.

Implementation ⬆ ⬇

amikacin
aminophylline
ascorbic acid
atracurium
atropine
aztreonam
benztropine
bumetanide
buprenorphine
butorphanol
calcium chloride
calcium gluconate
cefotaxime
cefotetan
cefoxitin
ceftazidime
ceftriaxone
cefuroxime
chlorpromazine
clindamycin
cyanocobalamin
cyclosporine
dexamethasone
digoxin
diphenhydramine
dobutamine
dopamine
doxycycline
enalaprilat
ephedrine
epinephrine
epoetin alfa
erythromycin
esmolol
famotidine
fentanyl
fluconazole
gentamicin
glycopyrrolate
heparin
hydroxyzine
insulin, regular
isoproterenol
labetalol
lidocaine
magnesium sulfate
mannitol
meperidine
metoclopramide
metoprolol
midazolam
minocycline
morphine
multivitamins
nalbuphine
naloxone
nitroglycerin
nitroprusside
norepinephrine
ondansetron
oxytocin
papaverine
penicillin G
pentamidine
phentolamine
phenylephrine
phytonadione
potassium chloride
procainamide
prochlorperazine
promethazine
propranolol
protamine
sodium bicarbonate
succinylcholine
sufentanil
theophylline
thiamine
tobramycin
vancomycin
vasopressin
verapamil

Y-Site Incompatibility:

Do not confuse pyridoxine with Pyridium or pralidoxime
Because of infrequency of single B-vitamin deficiencies, combinations are commonly administered.
- Administration of parenteral vitamin B₆ is limited to patients who are NPO or who have nausea and vomiting or malabsorption syndromes.
- Protect parenteral solution from light; decomposition will occur.
PO: DNC: Extended-release capsules and tablets should be swallowed whole, without crushing, breaking, or chewing. For patients unable to swallow capsule, contents of capsules may be mixed with jam or jelly.
IM: Rotate sites; burning or stinging at site may occur.
IV: May be administered slowly by IV push or as infusion in standard IV solutions. Monitor respiratory rate, heart rate, and BP when administering large IV doses.
- Pyridoxine-dependent seizures should cease within 2–3 min of IV administration.
Rate: Infusion rates of 15–30 min and up to 3 hr have been used.

Patient/Family Teaching ⬆ ⬇

Instruct patient to take medication as directed. If a dose is missed, it may be omitted because an extended period of time is required to become deficient in vitamin B₆.
Encourage patient to comply with diet recommended by health care professional. Explain that the best source of vitamins is a well-balanced diet with foods from the four basic food groups. Foods high in vitamin B₆ include bananas, whole-grain cereals, potatoes, lima beans, and meats.
Patients self-medicating with vitamin supplements should be cautioned not to exceed RDA. The effectiveness of megadoses for treatment of various medical conditions is unproved and may cause side effects, such as unsteady gait, numbness in feet, and difficulty with hand coordination.
Advise females of reproductive potential to notify health care professional if pregnancy is planned or suspected or if breastfeeding.
Emphasize the importance of follow-up exams to evaluate progress.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇